Wastegate control system and method

ABSTRACT

A wastegate control system and a method for the wastegate control system is disclosed. The wastegate control system includes an ambient pressure sensor, a throttle angle sensor, an ignition timing sensor, a knock sensor, an intake charge temperature sensor and an intake charge humidity sensor. A wastegate is controlled according to information received from these sensors.

CROSS REFERENCE TO RELATED APPLICATION

This application is a division of U.S. Pat. No. 8,333,071, U.S.application Ser. No. 12/243,760, entitled “Wastegate Control System andMethod”, filed on Oct. 1, 2008, which patent is incorporated byreference herein in its entirety.

BACKGROUND

The present invention relates to motor vehicles and in particular to awastegate control system and a method for controlling a wastegate.

Methods of controlling a wastegate have been previously proposed.Severinksy (U.S. patent number 2006/0237247) is directed at a hybridvehicle, including an internal combustion engine. Severinsky teaches awastegate that is implemented as a spring-loaded relief valve to limitthe boost provided. Furthermore, the wastegate of the Severinsky designmay take intermediate positions between fully-open and closed positions.Severinksky discloses the possibility of adjusting the wastegate torespond to an atmospheric-pressure signal provided by a suitable sensorto ensure that adequate boost is provided at higher altitudes to ensurevehicle performance.

Weinzierl (U.S. Pat. No. 7,104,352) is directed at an intercooler systemand a method for a snowmobile with a supercharged engine. Weinzierldiscloses a wastegate coupled to a turbine to allow for exhaust bypassof the turbine if the pressure of the charge air is too high.Furthermore, both the wastegate and the injector valve are controlled byan engine control unit, which makes use of inputs from an intercoolerliquid level sensor, a charge air temperature sensor, and a knocksensor, in addition to other conventional inputs to the engine controlunit.

Hartman (U.S. Pat. No. 6,779,344) is directed at a control system andmethod for a turbocharged throttled engine. In the Hartman design,engine exhaust flows from the engine to a turbocharger turbine and awastegate valve to the exhaust. The wastegate is controlled according toan algorithm. During one step of the algorithm, the desired manifoldpressure is retrieved according to an earlier step. A desired offset maybe added to the manifold pressure during another step, giving a desiredboost pressure value. The maximum boost is computed during another step.Hartman teaches that the maximum allowable pressure boost is computed ina known manner using the air flow rate and the known stored compressorcharacteristics. Following this, during the next step, the maximum boostis compared with the desired boost. If the desired boost is greater thanthe maximum boost, the desired boost is reset to equal the maximumboost. Otherwise, the desired boost level is kept the same. Duringanother step, the wastegate is controlled according to the desiredboost.

Wong (U.S. Pat. No. 6,694,242) is directed at a dual fuel engine havingmultiple dedicated controllers connected by a broadband communicationslink. The Wong design teaches a dual fuel engine that can operate in adual fuel mode or in a diesel only mode. Both dual fuel controller andthe diesel controller receive various types of inputs. In the Wongdesign, the dual fuel controller receives signals from a gas pressuresensor and a gas temperature sensor, and possibly other sensors. Thediesel controller receives signals from a timing/speed sensor (alsoconnected directly to dual fuel controller) and from a crankshaftspeed/timing sensor. The diesel controller may further receive signalsfrom a boost pressure sensor, an intake manifold air temperature sensor,an atmospheric air pressure sensor, an oil pressure sensor, a dieselfuel temperature sensor, an ambient temperature sensor as well aspossibly other sensors.

Based on data received and/or calculated from the various sensors, thedual fuel controller transmits signals to the gas injectors, the gasshut-off valve, and the turbo wastegate control valve. Also, the dieselcontroller operates according to signals received from the varioussensors, as well as signals received from the dual fuel controller.

Zimmer (U.S. Pat. No. 6,134,888) is directed at a turbocharger controlmanagement system. Zimmer teaches the use of an electronic turbochargercontrol system for an internal combustion engine that is provided tocontrol at least one turbocharger by controlling a bypass valve and awastegate in response to the engine speed, engine load, ambienttemperature and the operating environment's barometric pressure. Inparticular, a turbocharger control module has a plurality of enginecharacteristic signal inputs, including an intake manifold pressuresignal, an engine speed signal and an ambient temperature signal. Thesesignals are determined according to a manifold pressure monitor, anengine speed monitor and an ambient temperature monitor, respectively.Based on characteristic values for these signals, a predeterminedsetting for the wastegate is selected from a group of predeterminedsettings.

Houtz (U.S. Pat. No. 5,974,801) is directed at a turbocharger controlsystem. Houtz teaches a wastegate valve connected between the exhaustmanifold and the turbine section that is movable between an openposition at which fluid flow exhausted by the engine is free to bypassthe turbine and a closed position at which fluid flow exhausted by theengine is restricted from bypassing the turbine. Several sensors areincluded in the Houtz design that are used to determine a control signalfor the wastegate valve. The sensors include: a first means that sensesthe speed of crankshaft, used to determine the engine speed; a secondmeans to sense the boost pressure of the engine; a third means thatsenses a rack position of the engine; and a fourth means that senses thebarometric pressure of the engine environment.

Emmenthal (U.S. Pat. No. 4,322,948) is directed at an internalcombustion engine comprising an exhaust driven turbocharger forgenerating maximum boost pressure in the intake manifold. The Emmenthaldesign includes a knock sensor that detects engine detonation and, inresponse, causes actuation of a valve for temporarily reducing the boostpressure such that knocking subsides.

While the prior art teaches the use of several sensors that may beassociated with a wastegate controller, there are several shortcomings.The prior art lacks any use of a throttle angle sensor in associationwith a wastegate controller. Furthermore, the prior art lacks anyreference to an intake charge humidity sensor that may be associatedwith a wastegate controller. There is a need in the art for a wastegatecontrol system that makes use of a throttle angle sensor and an intakecharge humidity sensor.

SUMMARY

A method for controlling a wastegate in a turbocharger is disclosed.Generally, these methods can be used in connection with an engine of amotor vehicle. The invention can be used in connection with a motorvehicle. The term “motor vehicle” as used throughout the specificationand claims refers to any moving vehicle that is capable of carrying oneor more human occupants and is powered by any form of energy. The termmotor vehicle includes, but is not limited to cars, trucks, vans,minivans, SUV's, motorcycles, scooters, boats, personal watercraft, andaircraft.

In some cases, the motor vehicle includes one or more engines. The term“engine” as used throughout the specification and claims refers to anydevice or machine that is capable of converting energy. In some cases,potential energy is converted to kinetic energy. For example, energyconversion can include a situation where the chemical potential energyof a fuel or fuel cell is converted into rotational kinetic energy orwhere electrical potential energy is converted into rotational kineticenergy. Engines can also include provisions for converting kineticenergy into potential energy, for example, some engines includeregenerative braking systems where kinetic energy from a drivetrain isconverted into potential energy. Engines can also include devices thatconvert solar or nuclear energy into another form of energy. Someexamples of engines include, but are not limited to: internal combustionengines, electric motors, solar energy converters, turbines, nuclearpower plants, and hybrid systems that combine two or more differenttypes of energy conversion processes.

In one aspect, the invention provides a wastegate control systemassociated with a combustion device, comprising: a control unit incommunication with a wastegate and a throttle angle sensor, the throttleangle sensor configured to measure a throttle angle; and where thecontrol unit controls the wastegate according to information receivedvia the throttle angle sensor.

In another aspect, the control unit is in communication with an intakecharge temperature sensor.

In another aspect, the control unit is in communication with an intakecharge humidity sensor.

In another aspect, the control unit is in communication with an enginespeed sensor.

In another aspect, the control unit is in communication with an ambientpressure sensor.

In another aspect, the control unit is in communication with an ignitiontiming sensor.

In another aspect, the control unit is in communication with a knocksensor.

In another aspect, the invention provides a wastegate control systemassociated with a combustion device, comprising: a control unit incommunication with a wastegate and an intake charge humidity sensor; andwhere the control unit controls the wastegate according to informationreceived from the intake charge humidity sensor.

In another aspect, the control unit is in communication with an intakecharge temperature sensor.

In another aspect, the control unit is in communication with a throttleangle sensor.

In another aspect, the control unit is in communication with an enginespeed sensor.

In another aspect, the control unit is in communication with an ambientpressure sensor.

In another aspect, the control unit is in communication with an ignitiontiming sensor.

In another aspect, the control unit is in communication with a knocksensor.

In another aspect, the invention provides a method of controlling awastegate during cruise mode, comprising the steps of: receivinginformation from a throttle angle sensor; receiving information aboutcurrent cruise conditions; determining the power necessary to maintainthe current cruise conditions; selecting an intake air volume requiredto provide the necessary power; and controlling a wastegate to achievethe selected intake air volume.

In another aspect, the current cruise conditions include a currentvehicle speed.

In another aspect, there is a step of setting the throttle angle to awide open position.

In another aspect, there is a step of receiving a current engine speedfrom an engine speed sensor.

In another aspect, the current engine speed may be used to determine thepower necessary to maintain current cruise conditions.

In another aspect, the invention provides a method of controlling awastegate, comprising the steps of: receiving information from an intakecharge humidity sensor; determining the required boost pressurenecessary to eliminate ignition timing retard; and controlling awastegate to achieve the required boost pressure.

In another aspect, there is a step of receiving information from anintake charge temperature sensor.

In another aspect, there is a step of determining the required boostpressure necessary to eliminate ignition timing retard using informationreceived from the intake charge temperature sensor and informationreceived from the intake charge humidity sensor.

In another aspect, there is a step of receiving information from anignition timing sensor.

In another aspect, there is a step of determining the current ignitiontiming retard according to information received from the ignition timingsensor.

In another aspect, the method provides a method for controlling awastegate, comprising the steps of: receiving information associatedwith a combustion device from a plurality of sensors, the plurality ofsensors comprising an ignition timing sensor, an engine speed sensor, anintake charge temperature sensor and an intake charge humidity sensor;calculating a first boost pressure to achieve peak power usinginformation obtained from the ignition timing sensor and the enginespeed sensor; calculating a second boost pressure to achieve peak powerusing information obtained from the intake charge temperature sensor andfrom the intake charge humidity sensor; comparing the first boostpressure and the second boost pressure and selecting a minimum boostpressure that is the lesser of the first boost pressure and the secondboost pressure; and controlling a wastegate to achieve the minimum boostpressure.

In another aspect, the plurality of sensors includes a throttle anglesensor.

In another aspect, there is a step of receiving information from thethrottle angle sensor.

In another aspect, there is a step of controlling the wastegateaccording to information received from the throttle angle sensorwhenever the engine is in a cruise mode.

In another aspect, the plurality of sensors includes a knock sensor.

In another aspect, there is a step of controlling the wastegateaccording to information received by the knock sensor.

In another aspect, there is a step of controlling the wastegateaccording to a maximum allowed boost pressure whenever the engine isdetermined to be outside of a knock limited region, as determined byinformation received from the knock sensor.

Other systems, methods, features and advantages of the invention willbe, or will become, apparent to one of ordinary skill in the art uponexamination of the following figures and detailed description. It isintended that all such additional systems, methods, features andadvantages be included within this description and this summary, bewithin the scope of the invention, and be protected by the followingclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be better understood with reference to the followingdrawings and description. The components in the figures are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the invention. Moreover, in the figures, likereference numerals designate corresponding parts throughout thedifferent views.

FIG. 1 is a schematic view of an embodiment of a turbocharged enginesystem;

FIG. 2 is an embodiment of a flow chart of the process of controlling awastegate using an ambient pressure sensor;

FIG. 3 is an embodiment of a chart showing the relationship of allowedboost pressure to altitude;

FIG. 4 is an embodiment of a flow chart of the process of controlling awastegate using a knock sensor;

FIG. 5 is an embodiment of a flow chart of the process of controlling awastegate using a throttle angle sensor;

FIG. 6 is an embodiment of a flow chart of the process of controlling awastegate using a throttle angle sensor;

FIG. 7 is an embodiment of a chart showing the relationship of ignitiontiming to boost pressure;

FIG. 8 is an embodiment of a flow chart of the process of controlling awastegate using an ignition timing sensor;

FIG. 9 is an embodiment of a flow chart of the process of controlling awastegate according to intake charge conditions; and

FIG. 10 is an embodiment of a flow chart of the process of controlling awastegate according to information received by multiple sensors.

DETAILED DESCRIPTION

FIG. 1 is a schematic view of an embodiment of motor vehicle 101. Itshould be understood that the embodiment discussed here is not intendedto illustrate all of the components that are necessary for motor vehicle101 to function. Instead, the embodiment of motor vehicle 101 seen inFIG. 1 is only intended to illustrate some components of motor vehicle101, especially those components related to generating power and inparticular those components typically associated with an engine.

Motor vehicle 101 may include combustion device 102. For the purposes ofclarity, combustion device 102 is shown in FIG. 1 as a portion of anengine. Generally, combustion device 102 may be any kind of engine. Insome embodiments, combustion device 102 may be a hybrid power system.Additionally, combustion device 102 may comprise multiple engines.

Motor vehicle 101 may also be associated with intercooler 115.Intercooler 115 may be any type of intercooler, including, but notlimited to, a top mounted intercooler, a front mounted intercooler and av-mounted intercooler. In other embodiments, intercooler 115 may beanother type of intercooler. In some embodiments, wastegate controlsystem 100 may not include intercooler 115 or wastegate control system100 may include a different type of heat exchange device.

Motor vehicle 101 may further comprise turbocharger 150. Turbocharger150 may include turbine 152, as well as compressor 154. Turbocharger 150could be any type of turbocharger. In some embodiments, turbocharger 150could also be a supercharger.

Using the configuration described here, combustion engine 102,intercooler 115 and turbocharger 150 may work in conjunction tofacilitate the production of power within motor vehicle 101. In thisembodiment, air generally flows through each of various components 102,115 and 150 to facilitate the combustion of fuel within combustiondevice 102. Generally, components 102, 115 and 150 may collectively bereferred to as power system 103. In some embodiments, power system 103may include additional components that facilitate the exchange of airbetween components 102, 115 and 150.

The following is a brief description of an embodiment of the flow of airthrough power system 103. Generally, air enters power system 103 throughair inlet 156 of turbocharger 150. This ambient air may be compressedvia compressor 154 and then fed into intercooler 115 via first hosing172. After the air has moved through intercooler 115, the air mayproceed through throttle body 118 and intake manifold 106. Throttle body118 may include throttle valve 120 that may be used to regulate the flowof air to intake manifold 106. Finally, once the air has reached intakemanifold 106, it may enter combustion device 102 at intake port 174. Asthe air enters combustion device 102 it may be combined with fuel from afuel injector.

On the other side of combustion device 102, exhaust gas is expelledthrough outlet port 176, and continues along second hosing 178 until theexhaust gas is delivered to turbocharger 150. At this point, the exhaustdrives turbine 152 within turbocharger 150, which simultaneously spinscompressor 154. As air is drawn into turbocharger 150 at air inlet 156,the air is compressed and fed back into first hosing 172, to repeat thecycle over again. Also, the exhaust gas that drives turbine 152 isfinally expelled through exhaust port 158 of turbocharger 150.

Turbocharger 150 may include provisions for reducing the amount ofexhaust gas received at turbine 152. In this embodiment, turbocharger150 may include wastegate 160. Wastegate 160 may be configured to openand close in order to modify the amount of exhaust gas received atturbine 152. As the amount of exhaust gas received at turbine 152 isreduced, turbine 152 and compressor 154 may spin less rapidly, reducingthe boost pressure downstream of compressor 154. Likewise, as the amountof exhaust gas received at turbine 152 is increased, turbine 152 andcompressor 154 may spin more rapidly, increasing the boost pressuredownstream of compressor 154.

In some embodiments, power system 103 may include control unit 130.Control unit 130 may be a computer of some type configured to controlwastegate 160. In an embodiment, control unit 130 may include provisionsfor wastegate 160. Throughout the following detailed description,wastegate control system 100 refers collectively to control unit 130 andwastegate 160 as well as any other provisions that may facilitate theoperation of wastegate 160, including for example, various sensors.

In some embodiments, for example, wastegate control system 100 mayinclude provisions for determining the temperature and/or humidity ofthe air disposed within intake manifold 106 and introduced to combustiondevice 102. In some embodiments, intake manifold 106 may include varioussensors. In an embodiment, intake manifold 106 may include provisionsfor determining the temperature associated with intake manifold 106.Also, intake manifold 106 may include provisions for determining thehumidity associated with intake manifold 106.

Intake manifold 106 may include intake charge temperature sensor 112. Insome embodiments, intake charge temperature sensor 112 may be disposedwithin intake manifold 106. Generally, intake charge temperature sensor112 may be any device that measures the temperature of air within intakemanifold 106. In some embodiments, intake manifold 106 may also includeintake charge humidity sensor 114. Intake charge humidity sensor 114 maybe disposed within intake manifold 106.

Wastegate control system 100 may further include provisions fordetermining the current operating parameters of throttle body 118.Throttle body 118 may include throttle valve 120. Throttle valve 120 mayopen and close in a manner that changes the airflow rate into intakemanifold 106. In an embodiment, throttle body 118 includes throttleangle sensor 121. Throttle angle sensor 121 may be configured to measurethe angle of throttle valve 120 as measured from an initial position.

In some embodiments, wastegate control system 100 may include provisionsfor measuring various parameters associated with combustion device 102.In some cases, it may be important to know the current engine speed. Insome embodiments, wastegate control system 100 may include engine speedsensor 125. Engine speed sensor 125 may be associated with combustiondevice 102. For the purposes of illustration, engine speed sensor 125 isdisposed next to combustion device 102. However, in some embodiments,engine speed sensor 125 may be disposed on a portion of combustiondevice 102 not shown in this schematic illustration. In an embodiment,engine speed sensor 125 may be a crankshaft sensor.

In some cases, it may be important to determine other parametersassociated with the operating conditions of combustion device 102,including the current ignition timing and the knock level. Wastegatecontrol system 100 may include ignition timing sensor 131 as well asknock sensor 133. Using sensors 131 and 133, wastegate control system100 may be configured to respond to various operating conditions ofcombustion device 102.

Additionally, wastegate control system 100 may include provisions formeasuring ambient pressure outside of power system 103. Wastegatecontrol system 100 may include ambient pressure sensor 127. In someembodiments, ambient pressure sensor 127 may be disposed nearturbocharger 150 and in a position suitable to measure the ambientpressure. In other embodiments, ambient pressure sensor 127 may bedisposed anywhere on motor vehicle 101.

Control unit 130 may be in communication with wastegate 160, ambientpressure sensor 127, throttle angle sensor 121, engine speed sensor 125,ignition timing sensor 131, knock sensor 133, intake charge temperaturesensor 112 and intake charge humidity sensor 114. In some embodiments,control unit 130 may communicate with various devices by usingelectrical connections. Specifically, control unit 130 may be connectedto wastegate 160 by first connection 132. In a similar manner, controlunit 130 may be connected to the following sensors: to ambient pressuresensor 127 by second connection 134; to intake charge temperature sensor112 by third connection 136; to intake charge humidity sensor 114 byfourth connection 137; to throttle angle sensor 121 by fifth connection138; to ignition timing sensor 131 by sixth connection 140; to enginespeed sensor 125 by seventh connection 142; and to knock sensor 133 byeighth connection 144. These various connections could be electrical,optical or wireless.

As previously discussed, wastegate 160 may be controlled in order tomodify the boost pressure downstream of compressor 154. Various methodsfor controlling wastegate 160 using control unit 130 in association withone or multiple sensors 112, 114, 121, 125, 127, 131 and 133 will bediscussed throughout the remainder of this detailed description. Inparticular, wastegate control system 100 may be configured to controlwastegate 160 using information from particular sensors depending on thecurrent operating conditions of power system 103.

In one embodiment, wastegate control system 100 may be configured tocontrol wastegate 160 in response to changes in ambient pressure and/oraltitude, which are directly related to one another. Typically, enginesoperating in higher elevations may experience less knock than enginesoperating in lower elevations. During operating conditions where knockis less frequent, boost pressure may be increased in power system 103 inorder to achieve greater power. Therefore, wastegate control system 100may include provisions for increasing the boost pressure with increasingelevation. Likewise, wastegate control system 100 may include provisionsfor decreasing the boost pressure with decreasing elevation, asdecreasing the boost pressure may generally reduce the frequency ofknocking in operating conditions where knock may occur.

Referring to FIGS. 2 and 3, control unit 130 may control wastegate 160according to the ambient pressure. Flow chart 200 is one embodiment of amethod for controlling wastegate 160 according to the ambient pressure.During a first step 202, control unit 130 may determine the currentambient pressure as measured by ambient pressure sensor 127. Becauseambient pressure is related directly to altitude, the ambient pressurecan be used to estimate the current altitude. During a second step 204,control unit 130 may select an allowed boost pressure according to thecurrent altitude.

FIG. 3 is an embodiment of chart 300 used to determine the allowed boostpressure for various altitudes. In particular, as the altitude increasesthe allowed boost pressure increases, though not in a strictly linearmanner, as indicated by plotted line 302. By inputting a value for thecurrent altitude, as determined from the ambient pressure measurement,control unit 130 may determine the allowable boost pressure from asimilar type of chart or table. It should be understood that chart 300is only meant to illustrate a predetermined relationship betweenaltitude and allowed boost pressure. In other embodiments, plotted line302 may have a different shape, although the general trend of increasingthe allowed boost pressure with altitude still holds.

Following this, during a third step 206, control unit 130 may controlwastegate 160 according to the previously selected allowed boostpressure. In other words, control unit 130 may compute the volume of airwhich is based on the exhaust gas being received at turbine 152 in orderto achieve the allowed boost pressure via compressor 154. Using thiscomputed air volume, control unit 130 may the open or close wastegate160 in order to increase or reduce the gas volume being delivered intothe turbine 152 of the turbocharger 150. With this arrangement, powersystem 103 may generate increased power for higher altitude conditionswhere combustion device 102 is not knock limited.

Wastegate control system 100 may include further provisions foradjusting the boost pressure in order to reduce or eliminate knock incombustion device 102 whenever knock occurs under any operatingconditions. Generally, as previously discussed, the degree of knockingthat occurs in combustion device 102 may decrease as the boost pressureis decreased.

FIG. 4 is an embodiment of flow chart 400 of a method of controllingwastegate 160 according to the amount of knock experienced withincombustion device 102. During a first step 402, control unit 130 maydetermine the current knock level according to information received byknock sensor 133. Following this, during a second step 404, control unit130 compares the current knock level with a threshold to determine ifthe current knock level is acceptable. If the current level of knock isacceptable, control unit 130 proceeds to a third step 406, where thecurrent boost pressure is maintained. At this point, during a fourthstep 408, control unit 130 controls wastegate 160 to maintain thecurrent boost pressure.

If, during second step 404 the current knock level is found to be abovethe threshold, in other words the current knock level is unacceptable,control unit 130 may proceed to fifth step 410. During a fifth step 410,control unit 130 may lower the current boost pressure. Following this,during step 408, control unit 130 adjusts wastegate 160 accordingly inorder to lower the current boost pressure. Using this method, the amountof knocking within combustion device 102 may be reduced or eliminatedunder a variety of operating conditions.

In some embodiments, wastegate control system 100 may include provisionsfor adjusting boost pressure via wastegate 160 to accommodate thecurrent power demand. This is especially important in turbochargedengine systems where some lag may occur between the driver stepping onthe accelerator and the engine responding due to the distance betweenvarious components within power system 103 and the time it takes thepressurized air to travel between these various components. In order toreduce this lag time, power system 103, and in particular turbocharger150, may be configured to respond to power demands before the air withinpower system 103 has completed a full cycle through each of the variouscomponents.

The current power demand may be determined, for example, by consideringthe angle of the throttle valve. A higher throttle angle will beassociated with a higher power demand, and thus a higher boost pressuremay be supplied in order to accommodate the higher power demand.Likewise, a lower throttle angle will be associated with a lower powerdemand, and thus a lower boost pressure may be supplied in order toaccommodate the lower power demand.

FIG. 5 is an embodiment of flow chart 500 of a process for controllingwastegate 160 according to the current throttle angle. During a firststep 502, control unit 130 may determine the current throttle angle viainformation received by throttle angle sensor 121. Following this,during a second step 504, control unit 130 may predict the power demandof the engine according to the throttle angle. Next, during a third step506, control unit 130 calculates the required boost pressure necessaryto meet the current power demand. Finally, during a fourth step 508,control unit 130 controls wastegate 160 to achieve the required boostpressure.

In another embodiment, wastegate control system 100 could be configuredto control wastegate 160 in response to conditions related to cruisemode (cruise control). Typically, in cruise mode a constant vehiclespeed is set by a driver and maintained by control unit 130 usingthrottle valve 120 to control the air volume received into intakemanifold 106. In some embodiments, however, wastegate control system 100may include provisions for adjusting the boost pressure in a manner tomaintain a constant speed during cruise mode. In particular, rather thanusing throttle valve 120 to modify the air volume received at intakemanifold 106, wastegate 160 could be used to modify the required boostpressure to maintain a constant vehicle speed. In other words, wastegate160 could effectively be used to ‘throttle’ the air received at intakemanifold 106. In such cases, throttle valve 120 could be set to a wideopen angle.

FIG. 6 is an embodiment of flow chart 600 of a process for controllingwastegate 160 in order to maintain a constant cruising speed duringcruise mode. During a first step 602, control unit 130 sets throttlevalve 120 to wide open. Following this, during a second step 604,control unit 130 may determine the power necessary to maintain theconstant speed set for the cruise condition. This could be done, in someembodiments, from the current engine speed that is measured by enginespeed sensor 125. Next, during a third step 606, control unit 130calculates the intake air volume necessary to provide the required powerfor maintaining the current cruising speed. Finally, during a fourthstep 608, control unit 130 controls wastegate 160 in order to supply therequired air volume for maintaining the current cruising speed. Usingthis wide open throttle configuration, wastegate control system 100 mayreduce or substantially eliminate pumping losses and increase theefficiency of power system 103.

In another embodiment, wastegate control system 100 could be configuredto control wastegate 160 in response to ignition timing. Generally,there is an optimum balance between ignition timing and boost pressureat each engine speed and load. For example, FIG. 7 illustrates anembodiment of chart 700 showing an optimized relationship (indicated byline 702) between ignition timing and boost pressure at 1500 RPM and afixed engine load. Given a particular value for ignition timing, anassociated boost pressure may be found using chart 700 in order toachieve peak power.

FIG. 8 is an embodiment of flow chart 800 of a process for controllingwastegate 160 in order to achieve peak power for a given ignitiontiming, engine speed and engine load. During a first step 802, controlunit 130 may determine the current ignition timing value according toinformation received via ignition timing sensor 131. In an embodiment,information related to engine speed and/or engine load may also bedetermined during this step by receiving information from engine speedsensor 125 as well as possibly other sensors. Following step 802, duringa second step 804, control unit 130 may select an allowed boost pressurebased on the current values of the ignition timing, the engine speedand/or the engine load. Control unit 130 may refer to a look-up tableincluding information similar to the information displayed in chart 700,for example. Finally, during a final step 806, control unit 130 maycontrol wastegate 160 in order to achieve the allowed boost pressure asdetermined during the previous step 804.

In another embodiment, wastegate control system 100 may be configured tocontrol wastegate 160 in response to intake charge conditions. In somecases, unwanted ignition timing retard may occur due to knocklimitation. Wastegate control system 100 may include provisions forreducing this unwanted ignition timing retard. In some cases, wastegatecontrol system 100 may modify boost pressure using information relatedto intake charge conditions in order to reduce or substantiallyeliminate ignition timing retard.

FIG. 9 is an embodiment of a flow chart 900 of a process of controllingwastegate 160 in order to reduce or substantially eliminate ignitiontiming retard. During a first step 902, control unit 130 may determinethe intake charge temperature and humidity according to informationreceived via intake charge temperature sensor 112 and intake chargehumidity sensor 114. Following step 902, during a second step 904,control unit 130 may calculate an adjusted boost pressure in order toeliminate ignition timing retard. In some embodiments, the ignitiontiming retard could be known by control unit 130. In another embodiment,the ignition timing retard could be determined using ignition timingsensor 131. Finally, during a third and final step 906, control unit 130may control wastegate 160 in order to achieve the adjusted boostpressure calculated during the previous steps.

The previous embodiments demonstrate possible methods or processes forcontrolling wastegate 160 using information obtained by one or possiblyseveral sensors. In some embodiments, these various methods or processescould be combined and used in conjunction with one another. Thefollowing discussion applies to an embodiment of a method or process forcontrolling wastegate 160 using information from all of the sensorspreviously discussed, including: intake charge temperature sensor 112,intake charge humidity sensor 114, throttle angle sensor 121, enginespeed sensor 125, ambient pressure sensor 127, ignition timing sensor131 and knock sensor 133. It should be understood, however, that manyother possible configurations of each of the processes previouslydiscussed could be combined to create another process or method forcontrolling wastegate 160. In particular, using different methods forcontrolling wastegate 160 depending on different operating conditionsmay facilitate achieving maximum efficiency for combustion device 102.

FIG. 10 is an embodiment of a flow chart 1000 of a process forcontrolling wastegate 160 in order to achieve maximum efficiency forcombustion device 102 under various operating conditions. During step1002, control unit 130 may receive information related to varioussensors, including intake charge temperature sensor 112, intake chargehumidity sensor 114, throttle angle sensor 121, engine speed sensor 125,ambient pressure sensor 127, ignition timing sensor 131 and knock sensor133. Additionally, during step 1002, control unit 130 may receive otherinformation, including information related to engine load as well ascurrent vehicle speed or other information related to cruise modeconditions. Following step 1002, control unit 130 may determine ifcombustion device 102 is in a knock limited region during step 1004.Control unit 130 may make this decision on the basis of informationreceived by ambient pressure sensor 127, which can be further convertedto altitude information, as previously discussed. If combustion device102 is not in a knock limited region, control unit 130 may proceed tostep 1006. During step 1006, control unit 130 may control wastegate 160in order to achieve the maximum allowed boost pressure. In some cases,the maximum allowed boost pressure may be limited by various parameters,including injector duty, drive train restraints as well as otherrestraints associated with combustion device 102.

If, during step 1004, combustion device 102 is determined to be in aknock limited region, control unit 130 may then proceed to step 1008.During step 1008, control unit 130 determines if the motor vehicle isoperating in cruise mode. If the engine is operating in cruise mode,control unit 130 may proceed to step 1010. During step 1010, controlunit 130 may calculate the intake air volume necessary to maintain thecurrent cruising conditions, including the current or preset vehiclespeed. Following this, during step 1012, control unit 130 may setthrottle valve 120 to a wide open position, and then controls wastegate160 in order to achieve the necessary intake air volume calculatedduring step 1010.

If, during step 1008, the motor vehicle is determined not to be incruise mode, control unit 130 may proceed to step 1014 and step 1016simultaneously. During step 1014, control unit 130 may determine a firstboost pressure according to the current ignition timing value, as wellas engine speed and engine load. The current ignition timing value maybe received from ignition timing sensor 131 during step 1002. Likewise,the engine speed value may be received from engine speed sensor 125during step 1002. The engine load may be determined using informationfrom other sensors as well. During step 1016, control unit 130 maycalculate a second boost pressure according to the intake chargetemperature and the intake charge humidity, which may be received fromintake charge temperature sensor 112 and intake charge humidity sensor114, respectively.

Finally, following both steps 1014 and 1016, control unit 130 mayproceed to final step 1018. During step 1018, control unit 130 maycompare the first boost pressure determined during step 1014 and thesecond boost pressure determined during step 1016. Control unit 130 thenmay select the smaller of these two values and controls wastegate 160 inorder to achieve this selected boost pressure.

Using this method for controlling wastegate 160, power system 103 may beconfigured to achieve maximum power for the current operatingconditions.

While various embodiments of the invention have been described, thedescription is intended to be exemplary, rather than limiting and itwill be apparent to those of ordinary skill in the art that many moreembodiments and implementations are possible that are within the scopeof the invention. Accordingly, the invention is not to be restrictedexcept in light of the attached claims and their equivalents. Also,various modifications and changes may be made within the scope of theattached claims.

What is claimed is:
 1. A wastegate control system associated with acombustion device, comprising: a turbocharger including a wastegate anda turbine; a throttle valve configured to regulate air flow into thecombustion device; an ambient pressure sensor sensing an ambientpressure; a control unit in communication with the wastegate and incommunication with an intake charge humidity sensor sensing an intakecharge humidity; and wherein when the combustion device is operated in acruise control mode, the control unit: determines an allowed boostpressure based on the ambient pressure and the intake charge humidity;sets the throttle valve wide open, and controls the wastegate toincrease or decrease the volume of exhaust gas to be received at theturbine to achieve the allowed boost pressure.
 2. The wastegate controlsystem according to claim 1, wherein the control unit is incommunication with an intake charge temperature sensor, and wherein thecontrol unit also controls the wastegate according to informationreceived from the intake charge temperature sensor.
 3. The wastegatecontrol system according to claim 1, wherein the control unit is incommunication with a throttle angle sensor, and wherein the control unitalso controls the wastegate according to information received from thethrottle angle sensor.
 4. The wastegate control system according toclaim 1, wherein the control unit is in communication with an enginespeed sensor, and wherein the control unit also controls the wastegateaccording to information received from the engine speed sensor.
 5. Thewastegate control system according to claim 1, wherein the control unitis in communication with an ambient pressure sensor, and wherein thecontrol unit also controls the wastegate according to informationreceived from the ambient pressure sensor.
 6. The wastegate controlsystem according to claim 1, wherein the control unit is incommunication with an ignition timing sensor, and wherein the controlunit also controls the wastegate according to information received fromthe ignition timing sensor.
 7. The wastegate control system according toclaim 1, wherein the control unit is in communication with a knocksensor, and wherein the control unit also controls the wastegateaccording to information received from the knock sensor.
 8. A method ofcontrolling a wastegate in a turbocharger system of a combustion device,said turbocharger system including a turbine, comprising the steps of:operating the combustion device in a cruise control mode; setting athrottle valve in the combustion device wide open; receiving humidityinformation from an intake charge humidity sensor in the turbochargersystem; receiving temperature information from an intake chargetemperature sensor in the turbocharger system; selecting an increasedvolume of exhaust gas to be received at the turbine to achieve anincreased boost pressure in the turbocharger; and controlling thewastegate according to the received humidity information, the receivedtemperature information and the selected volume of exhaust gas.
 9. Themethod according to claim 8, wherein there is a step of determining therequired boost pressure necessary to eliminate ignition timing retardusing information received from the intake charge temperature sensor andinformation received from the intake charge humidity sensor.
 10. Themethod according to claim 8, wherein there is a step of receivinginformation from an ignition timing sensor, wherein the step ofcontrolling the wastegate includes controlling the wastegate accordingto the information received from the ignition timing sensor.
 11. Themethod according to claim 10, wherein there is a step of determining thecurrent ignition timing retard according to information received fromthe ignition timing sensor.
 12. A method for controlling a wastegate ina turbocharger system of a combustion device, wherein the turbochargersystem comprises a turbocharger and a turbine, comprising the steps of:operating the combustion device in a cruise control mode; receivinginformation associated with the combustion device from a plurality ofsensors, the plurality of sensors comprising a throttle angle sensor formeasuring a throttle angle and an ambient pressure sensor sensing anambient pressure; and before the combustion device has completed a fullcycle, controlling the wastegate according to the received informationto increase the volume of exhaust gas to be received at the turbine toincrease the boost pressure when the throttle angle is higher, and todecrease the volume of exhaust gas be received at the turbine todecrease the boost pressure when the throttle angle is lower.
 13. Themethod according to claim 12, wherein there is a step of controlling thewastegate according to information received from the throttle anglesensor whenever the engine is in a cruise mode.
 14. The method accordingto claim 12, wherein the plurality of sensors includes a knock sensor.15. The method according to claim 14, wherein there is a step ofcontrolling the wastegate according to information received by the knocksensor.
 16. The method according to claim 14, wherein there is a step ofcontrolling the wastegate according to a maximum allowed boost pressurewhenever the engine is determined to be outside of a knock limitedregion, as determined by information received from the knock sensor.